1. Field of the Invention
The present invention relates to a read only memory (ROM), and more particularly, to an apparatus for testing an on-chip ROM and a method thereof by which the contents stored in a ROM are tested within the chip, without being transferred externally, and only information as to whether or not there is a defect is output, such that the digital content of the ROM is protected.
2. Description of the Related Art
Contemporary microprocessors may include a ROM embedded therein as needed. For example, code that is executed during initialization, or “boot-up” of a processor, or code that is part of a subroutine that is frequently used in the system, may be stored in a ROM. Thus, during the manufacture of a microprocessor including a ROM that stores predetermined digital content, there is a test process for testing whether the content stored in the ROM is properly programmed.
In conventional systems, in order to test a ROM embedded in a chip (hereinafter referred to as an on-chip ROM), the chip mode of operation is set to a ROM test mode, a ROM test module within the chip exports the ROM data programmed in the ROM to an external test apparatus, and the external test apparatus compares the contents. Thus, the conventional approach, in which the ROM data stored in the on-chip ROM is read by the external test apparatus and it is determined whether or not there is an error, is relatively easy to implement and intuitive. However, the ROM data programmed in the on-chip ROM can be readily accessed during test mode. Thus, the conventional approach does not allow for the protection of digital content stored in the on-chip ROM in the case where it is desired that such content not be exposed to others.